Hot bar sealers- have heated tooling kept at a constant temperature (also known as Direct Contact Thermal Sealing). They use one or more heated bars, irons, or dies which contact the material to heat the interface and form a bond. The bars, irons and dies have various configurations and can be covered with a release layer or utilize various slick interposer materials (i.e. Teflon films) to prevent sticking to the hot tooling..